Cerebral cortex in the macaque monkey contains more than a dozen distinct areas that process visual information. The aim of the proposed research are to characterize the function, connections, and internal organization of some of these areas and in addition to identify and characterize new visual areas. To achieve these goals, we will use a combination of physiological techniques (single neuron recording from anesthetized, paralyzed animals) and anatomical techniques (tracing connections between areas and analyzing cortical architecture). The results should provide critical tests of our current hypothesis that visual cortex consists of a well-organized hierarchy of areas within which there are distinct functional streams for processing different types of visual information. Physiological recordings from areas V2, V3, and V4 will address issues concerning the distribution of color selective and orientation selective cells in these areas. By analyzing the responses to complex stimuli containing multiple orientations and/or multiple colors, we hope to ascertain how cells in these areas actually transform the messages relayed from lower visual centers. In conjuction with this, we will use anatomical techniques to study the internal architecture of V2, V3, V4, and the relationship of anatomical landmarks to functional clusters and columns. We will also use recording and pathway tracing techniques to characterize the layout of visual cortex in the parietal and temporal lobes. Particular emphasis will be placed on ascertaining the degree to which these regions, once thought to be relatively homogeneous, can be reliably subdivided into well-defined cortical areas.